The field of the disclosure relates generally to protecting a motor control circuit from damage, and more specifically, to protecting a motor control circuit and connected electronics from transient and/or ringing voltages.
Electric motors are used in countless varieties and applications worldwide. For example, electric motors are included within heating, ventilation, and air conditioning (HVAC) applications. A typical HVAC application includes a thermostat, a furnace or a fan coil, a system controller, a motor controller, and at least one electric motor. For example, a typical HVAC application includes a condenser, which includes a condenser motor, and a compressor, which includes a compressor motor.
Since the motor controller is a component within a larger system, the motor controller may be subject to transient voltages caused by, for example, initiated operation or discontinued operation of another component within the HVAC application. Furthermore, the motor controller may be subject to transient voltages caused by events external to the HVAC application, for example, power surges. Power surges may be caused by different external forces, most typically, from lightning strikes. Moreover, typical clamping circuits may not protect the motor controller from a transient voltage. A typical clamping circuit is positioned between the power source and a common mode choke. Even when the clamping device clamps the voltage to below a predefined level, the common mode choke may amplify the clamped voltage and deliver it to the motor controller in a ringing wave mode.